DE602004010500T2 - COMBINED HEAT AND POWER PLANT - Google Patents

Abstract

A splitter valve for splitting an inlet stream into a plurality of outlet streams. The valve comprising an inlet ( 31 ) and a plurality of outlets, one for each outlet stream. An outer sleeve ( 20 ) has a plurality of first outlet orifices ( 32, 33 ), one for each stream. An inner element ( 30 ) is moveably retained within the outer sleeve and has an inlet and a plurality of second outlet orifices ( 32, 33 ), one for each stream. The relative proportion of the inlet stream fed to each outlet is determined by the relative position of the inner element and outer sleeve. The first and second outlet orifices are shaped such that the flow through each outlet varies substantially linearly with the relative position of the inner element and outer sleeve.

Description

The The present invention relates to a combined heat and power Power system. In particular, the present invention relates to a combined heat and power system comprising a stirling engine with a head; one Burner to heat the Stirling engine head, so the Stirling engine can generate electrical energy; a heat exchanger which is so is arranged that he has heat from exhaust gases from the burner, which have heated the engine head, absorbed; and an auxiliary burner to generate additional heat which is instantaneous through the heat exchanger is absorbed.

One such combined heat and force system is hereinafter referred to as "of the type described".

One System of the type described is for domestic use Environment as a domestic combined Warmth- and force (dchp) system known. The Stirling engine delivers one Part of the domestic Electricity demand, with the rest of the main supply is delivered. The heating power of the Stirling engine supplies a Part of the domestic heat load, the remainder being supplied by the auxiliary burner. The Stirling engine burner and the auxiliary burner are modulated to the heating power required by the house to deliver, and the system is controlled to allow that the Stirling engine generates as much time as possible in terms of time.

however is subject to the range of heating power received by the burners can be due to the minimum flow requirements through a each of them restrictions. This results in a step change in the heating power when the engine burner capacity exceeded becomes. If the combined auxiliary and engine burners are both at minimum Settings work, they will produce a higher heating power when the burner generates at its maximum alone. This results in a poor control of the heating power in the intermediate Operating range. Because this is a critical operating area for the domestic Heating system could have turned out this problem in a reduction in the comfort of the user and the Efficiency of the system result.

According to the present Invention is, in a system of the type described, the auxiliary burner a multi-stage burner with separate stages that can be independently controlled / regulated are.

By the several independent ones controllable / controllable stages can be a more accurate control / regulation the heating power over the entire required area.

A greater flexibility is achieved if at least one stage has a heat output area, which differs from that of another stage. In practice can the heat output area each stage are made different.

Around even more flexibility introduce, At least one of the auxiliary burner stages may be arranged to both the heat exchanger to heat directly as well as the Stirling engine head. If thus ignited this stage will be without the engine burner is ignited, the Stirling engine work with reduced electrical power. If, however, this Stage is operated together with the engine burner, the Stirling engine is at the electrical peak power work.

Of the Additional burner can be located anywhere, provided that he a heat exchanger adequate Provide heat can. However, the auxiliary burner is preferably radially outside of the heat exchanger arranged as this is a cheaper Pack results.

Of the heat exchangers may be of any known construction, e.g. B. he can through a conduit may be provided which is surrounded by a water jacket is. However, the heat exchanger preferably comprises a helical coil or a plurality of series-connected helical coils for the Heat exchange fluid, which is wrapped around an axis and extending along the full axial length of the auxiliary burner extends. This results in an efficient way of Pack of a multi-stage burner, since this helix, the / the Burner stage (s) adjacent that is ignited in more efficient Way heat to be obtained.

Also With the helical coil arrangement, a part of the helix can thus be arranged be that he surrounds part of the Stirling engine head around the auxiliary burner stage provided so arranged around the Stirling engine head and the heat exchanger to warm immediately, as stated above.

Of the Stirling engine can be mounted so that its head is at the top as is known in the art. However, it is preferred The Stirling engine mounted so that his head is at the bottom and the Auxiliary burner and the heat exchanger are arranged directly under the head. An advantage of this arrangement is that it is a simple matter, a drain for liquids provided that has been condensed from the combustion gases are. Another advantage is that the engine is attached to at least one spring suspended which is attached to its upper end. Such Mounting allows easy access to the engine for routine maintenance and for laying water pipes to and from the engine.

An additional problem encountered in designing a heat exchanger for a dchp system has been in the removal of condensate from the helical tube within the auxiliary heat exchanger. Our earlier registration PCT / GB02 / 05711 discloses a heat exchanger having a tubing helically wound around a horizontal axis. With such an arrangement, a portion of the condensate collects on the horizontal surfaces of the pipeline.

It is common, to attach the Stirling engine to an elastic mounting to to swing the Stirling engine. The vibrations can be reduced be attached by an absorber mass elastic to the engine which can be tuned to out of phase with the Stirling engine to swing, thereby reducing the overall vibration. The Auxiliary elements of the system, such as the burners and the heat exchanger, are then attached separately from the Stirling engine.

however It has been found that when the heat exchanger on the Stirling engine is attached, a residual amount of vibration transmitted to the heat exchanger what will aid the removal of the condensate.

Prefers is the heat exchanger essentially only attached to the Stirling engine, so that it together vibrates with the engine.

Of the Engine must be dynamically balanced. Therefore, the preferred Mass of the heat exchanger balanced around the main axis of the invention. This avoids the need for complex balancing measures.

These Construction is particularly effective when the Stirling engine is mounted so that its head is at the bottom and the heat exchanger directly attached under the head.

Also Preferably, the heat exchanger comprises a Helical coil centered on the main axis of the motor. Of the Stirling engine has a major axis, which is preferably coaxial with a Axis is around which the helical coil is wound. By the heat exchanger arranges in this way, there are no horizontal surfaces, so that Condensate can flow down the pipes, assisted by the vibration transmitted by the Stirling engine.

One Example of the system according to the present invention Invention will now be described with reference to the accompanying drawings, wherein:

1 is a schematic cross section of the system;

2 is a schematic perspective view of the valve assembly; and

3 is a graphical representation of the valve sleeve opening profiles.

1 shows the entire Stirling engine assembly. It includes a Stirling engine 1 mounted in an "inverted" configuration, namely the engine head 2 at the bottom. The engine is on several springs 3 hung on a bearing bracket 4 are attached and the the engine 1 surround. Alternatively, it could also be hung on a single centrally located spring. An annular absorption mass 5 surrounds the engine and is characterized by a plurality of elastic bearings 6 tightened to absorb vibrations of the engine. The engine head 2 is with a plurality of annular ribs 7 which absorb heat in a manner to be described, thereby heating the engine head. The engine also has a radiator 8th which is recooled in a manner to be described by circulating water.

A heat exchanger is through a helical coil 10 provided coaxial with the Stirling engine 1 is. The sink 10 surrounds the lower end of the head 2 below the ribs 7 and then extends axially under the engine 1 , The sink 10 is provided in three separate stages. The first stage 11 surrounds the engine 2 , the second stage 12 lies under the engine head 2 and is of it by a partition plate 13 separated, which is perforated on its outer periphery. The third stage 14 is axially below the second stage 12 and is wound with a smaller radius than the first two steps. The third stage 14 is not surrounded by a burner. The flapper 13 keeps the temperature and pressure in the first and second stages 11 and 12 when the third stage 14 does not ignite. Also, the heat from the first and second stages 11 and 12 on the head 2 of the motor 1 reflected back.

The burner 2 has an annular configuration and surrounds the motor head and coil 10 , The burner 20 is also divided into levels. The first stage 21 surrounds the engine head 2 and the annular ribs 7 , A second stage 22 surrounds the lower end of the engine head 2 and the coils 11 the first stage. The third stage 23 the burner surrounds the coils 12 the second stage.

It should also be noted that the second and third burner stages 22 and 23 even in two lower levels 22A . 22B . 23A . 23B are divided, each of which is independently operable. Each of the first burner stage 21 , the second lower level 22A . 22B and the third sub-level 23A . 23B has a separate air and fuel gas supply along each like wires 30 . 31 . 32 . 33 and 34 , Each of the stages is also equipped with its own ignition system and a separate ignition control, so each can be ignited independently. It should also be noted that elsewhere in the description reference is made to "a burner for heating the Stirling engine" and "an auxiliary burner". These two burners can be part of a single multi-stage burner, as with respect to 1 described.

The control of the gas and air mixture is by a valve 40 achieved in more detail in the 2 and 3 is described.

The valve 40 includes an inner sleeve 41 and an outer sleeve 42 , For each outlet line, the inner and outer sleeves have 41 and 42 a pair of openings 43 . 44 different shapes when the inner and outer sleeves 41 and 42 be twisted relative to each other. The flow through each of the lines 30 to 34 is determined by the degree of overlap of the two openings. A solenoid 45 in the lower end of the housing with the valve 40 provides for the relative rotational movement between the inner and outer sleeves 41 and 42 ,

The relative sizes of the openings 43 . 44 are arranged to ensure that the flow through each outlet 30 to 34 as close as possible, a linear function of the rotational position of the inner and outer sleeves 41 and 42 is.

A detailed view of the opening profiles is in 3 specified. The hatched areas represent the projection of the openings 44 on a flat plane. 3 shows the positions for which the heating and power output are variable (VAR), maximum (MAX), minimum (MIN), or zero (NONE). It will be appreciated that independent control of all of these outlet streams is not achieved by all of the lines 30 to 33 possible to whom the fixed relationship between the two sets of openings 43 and 44 given is. However, it goes without saying 1 that a true independence of all stages of the burner is not absolutely necessary. For example, it will be for the second stage 22 be required, either the first lower grade 22a to ignite alone or this lower level in combination with the second lower level 22b to ignite. However, it will not be necessary the second grade 22b to ignite alone. Similar considerations apply to the second stage 23 , If greater independence is required, the inner sleeve can 41 be divided into a number of independently rotatable segments.

In operation, the operation of the Stirling engine assembly is determined by the domestic need for electricity and heat. When the demand for electricity is high and the need for heat is low, the first burner stage becomes 21 and optionally the second burner stage 22 ignited. On the other hand, when the demand for heat is high and the demand for electricity is low, the third burner stage becomes 23 and optionally the second burner stage 22 ignited. When the demand for both electricity and heat is high, all burner stages are fired. Within these extremes, there are a number of intermediate settings provided by the various burner stages and sub-stages, allowing a high degree of regulation of electrical energy generation.

Gas and air for the burners is placed in a blower / venturi gas valve assembly 46 mixed, and the speed of the blower can be regulated to vary the total amount of gas supplied to the various burner stages. The position of the inner sleeve 41 of the valve 40 inside the outer sleeve 42 is then determined according to the system requirements to ensure proper gas and air delivery to the various burner stages.

Alternatively, the gas may be with the air downstream of the valve 40 be mixed. This means that the valve 40 does not need to be sealed so that it allows a pre-mixing. However, this will be a gas / air mixer for any flow from the valve 40 require.

Water from the home central heating system is piped into the Stirling engine system 50 headed where it first the radiator 8th cool and then absorb some heat. It then circulates around a ring channel 51 around where there is a seal 52 between the burner 21 the first stage and the motor housing cools. Optionally, one or more cooling channels may direct the water around the outer casing of the burner. These channels can either be in series with or parallel to the channel 51 around the seal 52 be around. The water is then along the line 53 in the additional heat exchanger 10 directed. It initially runs around the third stage 14 where it absorbs relatively little heat since the third stage is not heated directly by a burner stage. It then circulates up through the helical windings through the second and first windings, respectively 12 and 11 where it is heated by the currently active burner stages, before finally moving along the line 54 exit to the domestic central heating system.

The exhaust gas from the various burner stages occurs along a chimney 60 out, while condensate from the exhaust gases along a condensate drain 61 which is arranged so as to avoid any dead space where liquid could build up and cause corrosion.

As in 1 can be seen, are the heat exchanger coil 10 and the burner assembly 20 via an annular carrier 55 directly at the Stirling engine 1 appropriate. Thus, the low residual vibration of the Stirling engine 1 that despite the effect of the absorption mass 5 remains transferred to the helix of the additional heat exchanger. Any condensate that deposits on the coils is caused to vibrate along the downwardly inclined surfaces of the coil by this vibration 10 ultimately to the condensate drain 60 to flow.

Claims (12)

Combined heat and power system comprising a Stirling engine ( 1 ) with a head ( 2 ); a burner ( 20 ) to heat the Stirling engine so that the Stirling engine can generate electrical energy; a heat exchanger arranged to absorb heat from exhaust gases from the burner that has heated the engine head; and an auxiliary burner ( 23 ) to generate additional heat, which is absorbed directly by the heat exchanger; wherein the auxiliary burner is a burner of several stages ( 23A ; 23B ) with separate stages which are independently controlled. The system of claim 1, wherein at least one Stage has a heat output area, which is different from that of another stage. A system according to claim 1 or claim 2, wherein at least one of the auxiliary burner stages is arranged such that they both the heat exchanger heated directly as well as the Stirling engine head. System according to one of the preceding claims, wherein which the auxiliary burner is radially outside the heat exchanger located. System according to one of the preceding claims, in which the heat exchanger comprises a helical coil ( 12 ) which is wound around an axis and which extends along the full axial length of the auxiliary burner. A system according to claim 5, when appended to claim 3, in which the helical coil also a part of the Stirling engine head surrounds. System according to one of the preceding claims, wherein which the Stirling engine is mounted in such a way that its head at the lowest point is and the auxiliary burner and the heat exchanger are directly under the head. The system of claim 7, wherein the engine of at least one feather hangs down, which is attached at its upper end. System according to one of the preceding claims, wherein which of the heat exchanger is mounted on the Stirling engine. A system according to claim 9, which is the heat exchanger essentially just mounted on the Stirling engine to work together to vibrate with the engine. The system of claim 10, wherein the engine is a Major axis of a reciprocating motion and the mass of the heat exchanger balanced around the main axis of the engine. A system according to claim 10 or 11, wherein the Burner is mounted together with the engine and the heat exchanger.